TY - JOUR
T1 - Long-lived dichotomous lineages of the proteasome subunit beta type 8 (PSMB8) gene surviving more than 500 million years as alleles or paralogs
AU - Tsukamoto, Kentaro
AU - Miura, Fumi
AU - Fujito, Naoko T.
AU - Yoshizaki, Goro
AU - Nonaka, Masaru
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2012/10
Y1 - 2012/10
N2 - On an evolutionary time scale, polymorphic alleles are believed to have a short life, persisting at most tens of millions of years even under long-term balancing selection. Here, we report highly diverged trans-species dimorphism of the proteasome subunit beta type 8 (PSMB8) gene, which encodes a catalytic subunit of the immunoproteasome responsible for the generation of peptides presented by major histocompatibility complex (MHC) class I molecules, in lower teleosts including Cypriniformes (zebrafish and loach) and Salmoniformes (trout and salmon), whose last common ancestor dates to 300 Ma. Moreover, phylogenetic analyses indicated that these dimorphic alleles share lineages with two shark paralogous genes, suggesting that these two lineages have been maintained for more than 500 My either as alleles or as paralogs, and that conversion between alleles and paralogs has occurred at least once during vertebrate evolution. Two lineages termed PSMB8A and PSMB8F show an A31F substitution that would probably affect their cleaving specificity, and whereas the PSMB8A lineage has been retained by all analyzed jawed vertebrates, the PSMB8F lineage has been lost by most jawed vertebrates except for cartilaginous fish and basal teleosts. However, a possible functional equivalent of the PSMB8F lineage has been revived as alleles within the PSMB8A lineage at least twice during vertebrate evolution in the amphibian Xenopus and teleostean Oryzias species. Dynamic evolution of the PSMB8 polymorphism through long-term persistence, loss, and regaining of dimorphism and conversion between alleles and paralogs implies the presence of strong selective pressure for functional polymorphism of this gene.
AB - On an evolutionary time scale, polymorphic alleles are believed to have a short life, persisting at most tens of millions of years even under long-term balancing selection. Here, we report highly diverged trans-species dimorphism of the proteasome subunit beta type 8 (PSMB8) gene, which encodes a catalytic subunit of the immunoproteasome responsible for the generation of peptides presented by major histocompatibility complex (MHC) class I molecules, in lower teleosts including Cypriniformes (zebrafish and loach) and Salmoniformes (trout and salmon), whose last common ancestor dates to 300 Ma. Moreover, phylogenetic analyses indicated that these dimorphic alleles share lineages with two shark paralogous genes, suggesting that these two lineages have been maintained for more than 500 My either as alleles or as paralogs, and that conversion between alleles and paralogs has occurred at least once during vertebrate evolution. Two lineages termed PSMB8A and PSMB8F show an A31F substitution that would probably affect their cleaving specificity, and whereas the PSMB8A lineage has been retained by all analyzed jawed vertebrates, the PSMB8F lineage has been lost by most jawed vertebrates except for cartilaginous fish and basal teleosts. However, a possible functional equivalent of the PSMB8F lineage has been revived as alleles within the PSMB8A lineage at least twice during vertebrate evolution in the amphibian Xenopus and teleostean Oryzias species. Dynamic evolution of the PSMB8 polymorphism through long-term persistence, loss, and regaining of dimorphism and conversion between alleles and paralogs implies the presence of strong selective pressure for functional polymorphism of this gene.
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U2 - 10.1093/molbev/mss113
DO - 10.1093/molbev/mss113
M3 - Article
C2 - 22491037
AN - SCOPUS:84866926984
SN - 0737-4038
VL - 29
SP - 3071
EP - 3079
JO - Molecular biology and evolution
JF - Molecular biology and evolution
IS - 10
ER -